A ducted fan fluid thrust vector propulsion system based on fluidics

Abstract

The jet-based ducted fan fluid thrust vector propulsion system belongs to the field of aviation power technology, and the system comprises an air inlet, a rotor, a stator and a tail nozzle arranged in series along an axis, and a duct flow channel is formed inside; a plurality of jet exciters in annular array distribution are embedded in the inner wall surface of the tail nozzle expansion section. The jet exciter is composed of a vibrating diaphragm and a resonance cavity, and an external control system outputs a high-frequency alternating signal to drive the vibrating diaphragm to vibrate at a high frequency, so that the gas in the cavity is periodically sucked and sprayed, forming a high-speed jet with zero net mass flow. The jet injects energy into the main flow boundary layer, induces the main flow to deflect based on the Coanda effect, and realizes omnidirectional thrust vector control. The present application does not need a mechanical deflection rudder surface and an external air source pipeline, has the advantages of compact structure, light weight, response without delay, low energy loss, and is suitable for electric vertical take-off and landing aircraft and tilting ducted fan propulsion systems.

Description

Technical Field

[0001] This invention relates to the field of aerospace propulsion technology, and in particular to a jet-based ducted fan fluid thrust vectoring propulsion system. Background Technology

[0002] With the rise of the low-altitude economy and the popularization of advanced air mobility concepts, electric vertical takeoff and landing (EVTOL) aircraft and tilt-rotor electric ducted fan propulsion systems have become research hotspots in the field of aerospace propulsion due to their high safety and low noise advantages. To achieve a smooth transition from vertical takeoff and landing to cruise and precise attitude control, the propulsion system must possess efficient and rapid-response thrust vectoring control capabilities. The main bottlenecks of existing traditional thrust vectoring schemes are: the large weight of traditional mechanical structures and the sluggish system response, resulting in large size and weight of vector propulsion systems and difficulties in high-frequency maneuver control, failing to meet the requirements of modern aircraft for lightweight design, easy layout, high efficiency, and high agility.

[0003] Efficient and lightweight airflow deflection control technology is crucial for ensuring the accurate and rapid response of thrust vectoring systems across the entire flight envelope. Currently, the mainstream thrust vectoring methods include mechanical vectoring, traditional aerodynamic vectoring, and hybrids of both. Traditional mechanical vectoring uses servo actuators to drive ball joint mechanisms or deflector plates to forcibly change the airflow direction. However, due to the physical inertia and friction inherent in mechanical structures, the response speed is limited, making it difficult to meet the demands of high-frequency transient maneuvers. Traditional aerodynamic vectoring utilizes high-pressure gas extracted from the compressor or duct for jet interference. While this reduces external moving parts, like mechanical vectoring, it requires a complex high-pressure bleed air piping system. These piping systems occupy a considerable volume and weight in the entire system, and directly drawing in the main working fluid leads to significant internal energy loss, hindering the miniaturization, weight reduction, and maximization of thrust efficiency in the aerospace field.

[0004] To address this, this invention, based on the principles of active flow control and jet-induced Coanda effect, constructs a jet-based ducted fan vector propulsion system. Airflow deflection no longer relies on an external air source; instead, a high-speed control airflow is spontaneously generated by a high-frequency vibrating diaphragm conformally embedded in the exhaust nozzle, directly injecting energy into the mainstream boundary layer. This provides a new approach to solving the structural dead weight and mechanical response hysteresis problems of aerospace thrust vectoring systems, as well as overcoming thrust loss and leakage defects in complex bleed air ducts. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of traditional mechanical thrust vectoring technology, such as complex structure, large weight, and mechanical response delay, as well as the problems of traditional aerodynamic vectoring systems, such as complex aerodynamic pipelines, large internal flow energy loss, and difficult overall layout. The invention provides a jet-based ducted fan fluid thrust vectoring propulsion system. The jet has a net mass flow rate of zero for the intake and exhaust of gas within one vibration cycle. By utilizing active flow control and the Coanda effect, thrust vectoring control is achieved without mechanical deflection control surfaces or internal duct air intake, thereby achieving the technical objectives of lightweight system structure, highly compact layout, and zero vector deflection delay.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A jet-based ducted fan fluid thrust vectoring propulsion system includes:

[0008] An intake duct, rotor, stator, and tail nozzle are arranged in series along the axial direction. The interiors of the intake duct, rotor, stator, and tail nozzle together form a duct flow channel for the flow of mainstream gas.

[0009] Multiple jet actuators are embedded in the inner wall of the expansion section of the tail nozzle and are distributed in a ring along the circumference of the tail nozzle.

[0010] An external control system is connected to the jet exciter via a signal cable and is used to output high-frequency alternating control signals;

[0011] The jet exciter includes a resonant cavity and a vibrating diaphragm disposed within the resonant cavity. The vibrating diaphragm serves as the movable wall of the resonant cavity and generates high-frequency vibration under the drive of the high-frequency alternating control signal, forcing the gas within the resonant cavity to be periodically drawn in and ejected through the jet orifice, forming a jet with a net mass flow rate of zero that is injected into the mainstream boundary layer.

[0012] The jet exciters are evenly distributed along the circumference of the tail nozzle.

[0013] The jet hole is located on the side of the resonant cavity facing the duct channel.

[0014] The external control system selectively activates the jet exciters at different locations, causing the mainstream gas to deflect in the corresponding direction, thereby achieving omnidirectional thrust vector control.

[0015] The present invention also includes a drive motor, which is mechanically connected to the rotor and is used to drive the rotor to rotate at high speed.

[0016] The jet generated by the jet exciter exchanges momentum with the mainstream, inducing the mainstream to adhere to the inner wall of the tail nozzle based on the Coanda effect and deflect.

[0017] The inner wall of the expansion section of the tail nozzle is embedded in the jet exciter.

[0018] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0019] 1. This invention is based on the principles of active flow control and jet-induced Coanda effect. The inlet, rotor, stator, and nozzle with embedded jet actuator are arranged in a streamlined tandem configuration along the axial direction. The main flow path and jet orifice positions are rationally designed to ensure smooth mixing of the control airflow with the main flow boundary layer, significantly improving aerodynamic vector deflection efficiency. Aerodynamic simulation results show that when the jet actuator is activated, the main flow fluid is smoothly mixed through the Coanda effect induced by the inner wall of the nozzle, and the deflection angle can be continuously and stably deflected from 0° to 10°. The inner wall of the nozzle and the jet actuator are directly connected in an embedded design, completely eliminating the complex mechanical deflection surfaces, ball joint mechanisms, and hydraulic transmission mechanisms found in traditional mechanical thrust vectoring technology. This greatly reduces the system weight and structural complexity, resulting in an extremely compact structure, extremely light weight, and zero-delay vector response. Experimental and numerical studies related to jets show that the response time of active jet control is as low as 2-6ms, which is about two orders of magnitude better than the 150-300ms delay of mechanical control, equivalent to "zero delay" at the macroscopic flight control level.

[0020] 2. To address the problems of complex pneumatic pipelines, large internal flow energy loss, and difficult overall layout of traditional pneumatic vector systems, this invention adopts a jet-based pure electric drive airflow control design. It utilizes the high-frequency vibration of a vibrating diaphragm under an external control signal to generate a high-speed control airflow, injecting energy into the mainstream boundary layer. This completely eliminates the need for physical air intake from inside the duct and the need for a complex external high-pressure air source pipeline system, greatly reducing the extra load on the system and completely eliminating the risk of high-pressure air leakage. Attached Figure Description

[0021] Figure 1 This is a schematic axial cross-sectional view of a jet-based ducted fan vector propulsion system.

[0022] Figure 2 This is a schematic diagram of the working flow path of a ducted fan vector propulsion system.

[0023] Figure 3 A schematic diagram showing the closed flow path of a ducted fan vector propulsion system.

[0024] Figure 4 This is a schematic diagram of the cross-section of the jet exciter arranged along the circumference of the nozzle.

[0025] Figure 5 This is a schematic diagram of the partial structure and working principle of the jet exciter.

[0026] Figure description: 1. Inlet duct, 2. Rotor, 3. Stator, 4. Tail nozzle, 5. Jet exciter, 51. Vibrating diaphragm, 52. Resonant cavity, 53. Jet orifice. Detailed Implementation

[0027] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Example 1

[0029] See Figure 1 This embodiment provides a jet-based ducted fan vector propulsion system, the main structure of which includes, in sequence, an air intake 1, a rotor 2, a stator 3, and a tail nozzle 4 arranged in series along the axial direction; the interiors of the air intake 1, rotor 2, stator 3, and tail nozzle 4 together form a ducted flow channel for the flow of mainstream gas;

[0030] The propulsion system in this embodiment also includes a drive motor, an external control system, and a jet exciter 5.

[0031] The drive motor and rotor 2 are mechanically connected, and the motor transmits power and torque to the rotor to drive the rotor to rotate at high speed.

[0032] The jet exciter 5 is provided in multiple forms and is embedded in the inner wall surface of the expansion section of the tail nozzle 4, specifically, as shown in... Figure 4 As shown, multiple jet actuators are evenly distributed in an array along the inner circumference of the nozzle. This ring array arrangement allows the system to achieve omnidirectional thrust vector deflection control by selectively activating actuators in different orientations.

[0033] The external control system is connected to the jet exciter 5 via a signal cable, and outputs a high-frequency alternating control signal to drive the vibrating diaphragm inside the jet exciter.

[0034] See Figure 5 The jet exciter 5 includes a resonant cavity 52 and a vibrating diaphragm 51 disposed in the resonant cavity 52. ​​A jet hole 53 is provided on one side of the resonant cavity 52, and the jet hole faces the duct flow channel of the tail nozzle 4.

[0035] The vibrating diaphragm 51 serves as the movable wall of the resonant cavity 52. ​​Driven by the high-frequency alternating control signal, it generates high-frequency vibration, thereby periodically changing the internal volume of the cavity. This forces the gas inside the resonant cavity 52 to be periodically drawn in and ejected through the jet hole 53, forming a jet with a net mass flow rate of zero that is injected into the mainstream boundary layer.

[0036] The gas flow path of the ducted fan vector propulsion system of this invention is as follows: Figure 2 As shown, rotor 2 provides the main power source for the entire propulsion system. The high-speed rotation of rotor 2 generates negative pressure, drawing in a large volume of air from the atmosphere through intake 1. The gas entering the system is accelerated by the work done by rotor 2 and rectified by stator 3, forming a stable, high-speed mainstream that enters the tail nozzle 4. In the tail nozzle 4, the mainstream gas expands, does work, and is then discharged. At this time, the diaphragm of the jet exciter 5 is controlled to vibrate at high frequency, forcing the gas in the resonant cavity to alternately be drawn in and ejected, injecting a "zero-mass" control airflow at high speed into the mainstream boundary layer. The ejected control airflow exchanges momentum with the mainstream, inducing the mainstream gas to deflect to one side based on the Coanda effect before being discharged, thus generating vector thrust. Precise vector deflection can be achieved without a complex external mechanical transmission system. The gas flow path after the ducted fan vector propulsion system is shut down is shown below. Figure 3 As shown.

[0037] This embodiment provides typical design parameters, material selection, and operating conditions for applying the present invention. Regarding the material selection of the core components, the vibrating diaphragm within the jet exciter is driven by piezoelectric ceramic. In terms of key geometric dimensions, the jet orifice 53 embedded in the inner wall of the tailpipe has a width of 1 mm, the resonant cavity 52 has a length of 4 mm and a width of 2 mm, and the spacing between each jet orifice is 5 mm. Regarding the driving voltage parameters, the vibration excitation frequency range is 10 Hz to 500 Hz, the amplitude is 100 V to 300 V, and the waveform is a square wave or a sine wave. The peak velocity of the jet is 40 m / s to 160 m / s. The following implementation case is an aerodynamic simulation conducted under takeoff conditions. The ducted fan speed is 4250 rpm, the inlet flow is an ideal gas with a static temperature of 288.15 K, a static pressure of 101325 Pa, and a velocity of 1 m / s. The boundary conditions of the jet orifice are set to a peak velocity of 60 m / s, a frequency of 500 Hz, a period of 0.002 s, and a sinusoidal distribution. When the jet exciter is off, the axial thrust is 2214.5 N, the circumferential thrust is 0 N, the power is 102.1 kW, the thrust-to-power ratio is 21.69 N / kW, and the deflection angle is 0°. When the jet exciter is on, the axial thrust is 2173.5 N, the circumferential thrust is 380.45 N, the power is 91.742 kW, the thrust-to-power ratio is 23.70 N / kW, and the deflection angle is approximately 10°. When the jet exciter is turned on during takeoff, the thrust-to-power ratio increases by 9.26%, and the deflection angle is continuously and stably deflected from 0° to 10°.

[0038] In summary, this invention, based on the principle of active flow control, proposes an innovative design concept for ducted fans: constructing a fluid thrust vectoring nozzle without mechanical moving parts, utilizing internally arranged jet exciters to regulate airflow. This invention fully leverages jet excitation to design thrust vectors for the airflow under multiple operating conditions in the nozzle, dynamically changing the mainstream direction and suppressing boundary layer separation solely through fluid interaction. This system achieves flexible omnidirectional thrust vector deflection without completely eliminating mechanical moving parts, featuring a compact structure, light weight, and zero-delay response. It effectively ensures smooth flow, improving the overall aerodynamic efficiency of the propulsion system and enhancing its adaptability to multiple operating conditions.

[0039] It should be understood that the application of this invention is not limited to the detailed structure and arrangement of the components presented in this specification. This invention can have other embodiments and can be implemented and carried out in various ways. The foregoing variations and modifications fall within the scope of this invention.

Claims

1. A jet-based ducted fan fluid thrust vector propulsion system, characterized in that, include: An intake duct (1), a rotor (2), a stator (3), and a tail nozzle (4) are arranged in series along the axial direction. The interiors of the intake duct (1), the rotor (2), the stator (3), and the tail nozzle (4) together form a duct flow channel for the flow of mainstream gas. Multiple jet exciters (5) are embedded in the inner wall of the expansion section of the tail nozzle (4) and are distributed in a ring along the circumferential direction of the tail nozzle (4). An external control system is connected to the jet exciter (5) via a signal and is used to output a high-frequency alternating control signal; The jet exciter (5) includes a resonant cavity (52) and a vibrating diaphragm (51) disposed in the resonant cavity (52). The vibrating diaphragm (51) serves as the movable wall of the resonant cavity (52) and generates high-frequency vibration under the drive of the high-frequency alternating control signal, forcing the gas in the resonant cavity (52) to be periodically drawn in and ejected through the jet hole (53) to form a jet with a net mass flow rate of zero that is injected into the mainstream boundary layer.

2. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: The jet exciter (5) is evenly distributed along the circumference of the tail nozzle (4).

3. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: The jet hole (53) is located on the side of the resonant cavity (52) facing the duct channel.

4. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: The external control system selectively activates the jet exciters (5) at different locations to deflect the mainstream gas in the corresponding direction, thereby achieving omnidirectional thrust vector control.

5. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: It also includes a drive motor, which is mechanically connected to the rotor (2) and is used to drive the rotor (2) to rotate at high speed.

6. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: The jet generated by the jet exciter (5) exchanges momentum with the mainstream gas, inducing the mainstream gas to adhere to the inner wall of the tail nozzle (4) and deflect based on the Coanda effect.

7. The jet-based ducted fan fluid thrust vector propulsion system as described in claim 1, characterized in that: The inner wall of the expansion section of the tail nozzle (4) is embeddedly connected to the jet exciter (5).

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